Does ‘speculation’ sometimes push asset prices much higher than fundamental values, leading to sharp and sudden falls in prices (“corrections”)?

Question 1(a) Distinguish the different definitions of “financial market efficiency”, explaining their implications for the predictability and variability of market prices.
(b) Does ‘speculation’ sometimes push asset prices much higher than fundamental values, leading to sharp and sudden falls in prices (“corrections”)?
Question 2(a) Are asset markets (e.g. stock markets, bonds, real estate prices) excessively volatile relative to ‘fundamentals’ i.e. reasonable estimates of the present discounted value of future cash flows from these assets?
(b) US stock prices – the S&P 500 index – rose by around 300% between February 2009 and September 2018. Is it possible to determine if this increase was a speculative bubble that will eventually reverse?